In Reply.—I agree with Dr Miles and colleagues that the assessment of tumor burden and prognosis based on pretreatment data is highly uncertain. Unfortunately, without performing a radical prostatectomy, this is all the information available to patients and clinicians (beyond age and comorbidity) to arrive at an appropriate decision regarding treatment. Relying on pretreatment data such as serum PSA and tumor grade to predict treatment outcomes carries risks of both undertreatment and overtreatment. Precisely because pretreatment data are uncertain, clinicians must use this information from a population perspective to maximize the probability of suggesting an optimal treatment strategy for the majority of their patients. This is the essence of formal decision analysis.Watchful waiting is delayed therapy and entails periodic reevaluation of available clinical data. Miles et al correctly state that the probability of cure with aggressive interventions likely is highest when patients are treated as early as possible.